Docker核心原理-资源隔离和限制

通常情况运行docker容器没有指定具体哪个cpu和内存的分配，其实docker官方给出了，docker容器可以运行在指定CPU上通过docker run --help可以看到:
先制作docker镜像:
编写Dockerfile

[root@linux-node1 ~]# cd stress/
[root@linux-node1 stress]# cat Dockerfile
FROM centos
ADD  epel-6.repo  /etc/yum.repos.d/
RUN  yum -y install stress && yum clean all
ENTRYPOINT ["stress"]
[root@linux-node1 stress]#
[root@linux-node1 stress]# docker build -t stress .
Sending build context to Docker daemon 4.096 kB
Step 1 : FROM centos
---> 970633036444
Step 2 : ADD epel-6.repo /etc/yum.repos.d/
---> 77600d6b488e
Removing intermediate container f141f47cb34f
Step 3 : RUN yum -y install stress && yum clean all
---> Running in 0949035c73da
Loaded plugins: fastestmirror, ovl http://mirrors.aliyuncs.com/epel/6/x86_64/repodata/98697cba0d79c083725de0c38b11c15878b35f5e27262becc02cd7ed1a13ac22-updateinfo.xml.bz2: [Errno 12] Timeout on http://mirrors.aliyuncs.com/epel/6/x86_64/repodata/98697cba0d79c083725de0c38b11c15878b35f5e27262becc02cd7ed1a13ac22-updateinfo.xml.bz2: (28, 'Connection timed out after 30001 milliseconds')
Trying other mirror.
Determining fastest mirrors
* base: mirrors.zju.edu.cn
* epel: mirrors.aliyun.com
* extras: mirrors.zju.edu.cn
* updates: mirrors.cqu.edu.cn
Resolving Dependencies
--> Running transaction check
---> Package stress.x86_64 0:1.0.4-4.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package          Arch             Version                 Repository      Size
================================================================================
Installing:
stress           x86_64           1.0.4-4.el6             epel            36 k
Transaction Summary
================================================================================
Install  1 Package
Total download size: 36 k
Installed size: 89 k
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : stress-1.0.4-4.el6.x86_64                                    1/1
install-info: No such file or directory for /usr/share/info/stress.info
Verifying  : stress-1.0.4-4.el6.x86_64                                    1/1
Installed:
stress.x86_64 0:1.0.4-4.el6
Complete!
Loaded plugins: fastestmirror, ovl
Cleaning repos: base epel extras updates
Cleaning up everything
Cleaning up list of fastest mirrors
---> 504c747b9b51
Removing intermediate container 0949035c73da
Step 4 : ENTRYPOINT stress
---> Running in ea8d8eb8fb87
---> 7e1e0e5cf825
Removing intermediate container ea8d8eb8fb87
Successfully built 7e1e0e5cf825
[root@linux-node1 stress]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED              SIZE
stress              latest              7e1e0e5cf825        About a minute ago   214 MB
ningx-file          v01                 460b5af495c4        3 days ago           531.9 MB
nginx/ningx         1.9.3v02            097c98e3cb2b        3 days ago           534.6 MB
nginx               1.9.3               d2cfb9ed3f2b        3 days ago           534.6 MB
docker.io/centos    latest              970633036444        11 days ago          196.7 MB
[root@linux-node1 stress]#

查看docker run命令帮助输出:

[root@linux-node1 stress]# docker run --help|grep cpu
--cpu-shares                    CPU shares (relative weight)
--cpu-period                    Limit CPU CFS (Completely Fair Scheduler) period
--cpu-quota                     Limit CPU CFS (Completely Fair Scheduler) quota
--cpuset-cpus                   CPUs in which to allow execution (0-3, 0,1)
--cpuset-mems                   MEMs in which to allow execution (0-3, 0,1)
[root@linux-node1 stress]#

启动一个容器:

[root@linux-node1 stress]# docker run  -it --rm --cpuset-cpus=0 stress --cpu 1
stress: info: [1] dispatching hogs: 1 cpu, 0 io, 0 vm, 0 hdd

在另外一个窗口查看使用情况cpu:

[root@linux-node1 ~]# top
top - 00:55:15 up 13:39,  2 users,  load average: 0.58, 0.47, 0.69
Tasks: 406 total,   2 running, 404 sleeping,   0 stopped,   0 zombie
%Cpu0  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  0.3 us,  0.3 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :   773004 total,   204488 free,   194528 used,   373988 buff/cache
KiB Swap:  2098172 total,  2096324 free,     1848 used.   399644 avail Mem
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
5944 root      20   0    7260     92      0 R 100.0  0.0   0:52.46 stress
335 root      20   0       0      0      0 S   0.3  0.0   1:17.95 kworker/3:1
1569 root      20   0  553044  13624   2952 S   0.3  1.8   0:13.46 tuned
4779 root      20   0       0      0      0 S   0.3  0.0   0:02.25 kworker/1:1
5946 root      20   0  157948   2504   1548 R   0.3  0.3   0:00.18 top

同样，再开启一个窗口:

[root@linux-node1 stress]# docker run  -it --rm stress --cpu 1
stress: info: [1] dispatching hogs: 1 cpu, 0 io, 0 vm, 0 hdd

再查切换到其他窗口查看cpu使用情况

[root@linux-node1 ~]# top
top - 00:57:52 up 13:41,  3 users,  load average: 1.50, 0.96, 0.84
Tasks: 414 total,   2 running, 412 sleeping,   0 stopped,   0 zombie
%Cpu0  :100.0 us,  0.0 sy,  0.0 ni,  0.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu2  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu3  :  0.0 us,  2.7 sy,  0.0 ni, 97.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :   773004 total,   195560 free,   199560 used,   377884 buff/cache
KiB Swap:  2098172 total,  2096576 free,     1596 used.   393660 avail Mem
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND

注意命令:
docker run -it --rm stress --cpu 1
docker run -it --rm --cpuset-cpus=0 stress --cpu 1
--cpuset-cpus后面跟cpu总个数，为docker容器指定的，而--cpu是用多少个cpu来运行，只能是1、2、3、4 ...N等等